LP85

LP85 Landscape

Soil Profile Morphology

Surface Soil

A1	0-15 cm	Dark brown (7.5YR3/4); light fine sandy clay loam; weak to moderate medium blocky structure; strong consistence dry; pH 6.3; abrupt change to:	LP85 Profile
A2	15-25 cm	Yellowish red (5YR4/6); light fine sandy clay loam; structureless; firm to strong consistence dry; contains a few (2%) quartz (2-4 mm diameter); pH 7.1; clear change to:
Subsoil
B21	25-45 cm	Yellowish red (5YR4/6); medium heavy clay; structured (with shiny faced peds); strong consistence dry; pH 8.1; gradual change to:
B22	45-60 cm	Red (2.5YR4/8); medium heavy clay; strong consistence dry; pH 8.5; clear change to:
B23	60-70 cm	Yellowish red (5YR5/6) with reddish yellow (7.5YR6/6) mottles; medium clay; weak consistence moist; contains many (25%) ferromanganiferous concretions (approximately 8 mm diameter); pH 8.9; clear change to:
B31	70-90 cm	Strong brown (7.5YR5/6) and yellowish red (5YR5/8); medium clay; structured (with smooth faced peds); weak consistence moist; contains very few (2%) manganese concretions (<8 mm diameter) and few (5-10%) quartz gravels (2-4 mm diameter); pH 8.9; gradual change to:
B32	90-120 cm	Yellowish brown (10YR5/4) with red (2.5YR4/8) mottles; medium clay; moderate fine polyhedral structure; very strong consistence dry; contains a common (10%) amount of quartz gravel (2-5 mm diameter); pH 8.9.

• Strong texture contrast between surface (A) horizons (<20% clay) and subsoil (B21) horizons (45% clay).
• Sodic subsoil.

	pH	Salinity Rating	Sodicity	Dispersion
Surface (A1 horizon)	slightly acid	very low	non-sodic	none1
Subsoil (B21 horizon)	moderately alkaline	very low	sodic	moderate-strong
Deeper subsoil (at 1 m)	strongly alkaline	very low - low	sodic	moderate-strong
1 Moderate dispersion after remoulding.

Horizon	Horizon Depth	pH (water)	pH CaCl2	EC 1:5	NaCl	Exchangeable Cations
						Ca	Mg	K	Na
						meq/100g
A1	0-15	6.3	5.3	0.05		6.1	1.3	0.6	0.1
A2	15-25	7.1	5.9	<0.05		3.5	1.9	0.6	0.3
B21	25-45	8.1	6.7	0.08		6.4	5.9	1.2	1.1
B22	45-60	8.5	7.1	0.12		6.4	6.7	1.3	1.5
B23	60-70	8.9	7.8	0.17		6.7	8.6	1.6	2.2
B31	70-90	8.9	7.8	0.15		7.8	12	2.2	2.8
B32	90-120	8.9	7.5	0.21		6.8	10	2	2.7

Horizon	Horizon Depth	Ex Al mg/kg	Ex Ac meq/100g	Field pF2.5	Wilting Point pF4.2	Coarse Sand (0.2-2.0mm)	Fine Sand (0.02-0.2mm)	Silt (0.002-0.02mm)	Clay (<0.002mm)
A1	0-15			19.2	6.8	12	48	25	17
A2	15-25			15.5	6.6	8	42	26	20
B21	25-45			27.9	15.3	11	26	17	45
B22	45-60			28	15.4	12	26	16	45
B23	60-70
B31	70-90
B32	90-120

Management Considerations:

Whole Profile

• Soluble salt levels are low throughout the profile and will not affect cropping.
• Plant Available Water capacity (PAWC) is estimated to be medium (approximately 115 mm) for this site. This is based on available laboratory data and assumes an effective rooting depth of 90 cm.

• The surface soil has a moderate overall nutrient status. The total nitrogen and organic carbon levels, however, are relatively low. Improving organic matter levels will assist in minimising structural problems such as surface sealing and hardsetting, as well as improving soil fertility and water holding capacity. Soils such as these with high fine sand (48%) and silt (25%) contents rely, to a large extent, on organic matter for soil aggregation.
• When dry, the soil becomes hard and may be difficult to work. If cultivated when dry it will become "powdery" and subsequent rain will result in surface sealing developing. The soil disperses moderately when remoulded which indicates that excessive cultivation or overstocking when the soil is wet may lead to surface crusting and exacerbate soil cloddiness as well as the hardsetting condition. Gypsum application may assist in reducing this structural deterioration. A bare cultivated soil is also likely to suffer structural damage from raindrop action. A cover of plants or stubble will provide some protection.
• The surface soil slakes when rapidly wet and is therefore prone to surface sealing. Improving organic matter levels will assist in improving soil aggregation and minimising slaking. Organic matter levels will improve by utilising practises such as minimum tillage, pasture rotation and stubble retention.
• The subsurface (A2) horizon disperses strongly in water (and disperses completely after remoulding). If excessively cultivated in a moist to wet condition it may develop into a plough pan.

• The subsoil is sodic and disperses moderately to strongly in water. This is likely to result in water and root movement being restricted. Deep tillage together with gypsum application has been advocated as an ameliorative technique for some soils (Jayawardene and Chan, 1994). A test strip in the paddock could be used to assess any benefits from such a technique.
• The deeper subsoil (from 60 cm depth) is strongly alkaline which indicates that some nutrients (e.g. copper, iron, manganese, and zinc) may be poorly available to deeper rooted plants.

• Better cropping soil than Site LP84.
• Gypsum (1 tonne per acre) applied in 1988 and 1991. Crop yields improved significantly as a result.
• Lime (1 tonne per acre) applied in 1993.
• Agroplough used.

• Profile described by Mark Imhof, Paul Rampant and Karen De Plater (4/7/95)